北京航空航天大学朱禹洁团队报道了4.5 V锂金属电池用无氟醚溶剂稀释电解质。相关研究成果发表在2024年7月10日出版的《德国应用化学》。

醚类溶剂有限的氧化稳定性对其在高压锂金属电池（LMBs）中的应用提出了重大挑战。为了解决这个问题，主流策略要么采用高浓度的氟化盐，要么依赖于高氟化溶剂，这将显著增加制造成本并造成严重的环境危害。

该文中，研究人员提出了一种替代和可持续的盐工程方法，以使由无氟醚组成的稀释电解质能够在高压LMBs中得到利用。所提出的0.8M电解质促进稳定的锂镀层剥离，具有99.47%的高库仑效率，并有效地缓解了LiNi_0.8Co_0.1Mn_0.1O₂（NCM811）阴极在充电到高电压时的金属溶解、相变和气体释放问题。

因此，4.5V高负载Li||NCM811电池在300次循环后显示出75.2%的容量保持率。多模式实验表征和理论研究表明，含硼盐在阳极和阴极上形成钝化层方面起着关键作用。

该简单且具有成本效益的电解质设计策略为在高压LMBs中，使用商业成熟、环境友好和低成本的无氟醚，提供了一条有前途的替代途径。

附：英文原文

Title: Dilute Electrolytes with Fluorine-free Ether Solvents for 4.5 V Lithium Metal Batteries

Author: Yusi Yang, Xiaofang Wang, Jiacheng Zhu, Lulu Tan, Nan Li, Yifan Chen, Linlin Wang, Ziqiang Liu, Xiayin Yao, Xuefeng Wang, Xiao Ji, Yujie Zhu

Issue&Volume: 2024-07-10

Abstract: The limited oxidation stability of ether solvents has posed significant challenges for their applications in high-voltage lithium metal batteries (LMBs). To tackle this issue, the prevailing strategy either adopts a high concentration of fluorinated salts or relies on highly fluorinated solvents, which will significantly increase the manufacturing cost and create severe environmental hazards. Herein, an alternative and sustainable salt engineering approach is proposed to enable the utilization of dilute electrolytes consisting of fluorine (F)-free ethers in high-voltage LMBs. The proposed 0.8 M electrolyte supports stable lithium plating-stripping with a high Coulombic efficiency of 99.47% and effectively mitigates the metal dissolution, phase transition, and gas release issues of the LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode upon charging to high voltages. Consequently, the 4.5 V high-loading Li||NCM 811 cell shows a capacity retention of 75.2% after 300 cycles. Multimodal experimental characterizations coupled with theoretical investigations demonstrate that the boron-containing salt plays a pivotal role in forming the passivation layers on both anode and cathode. The present simple and cost-effective electrolyte design strategy offers a promising and alternative avenue for using commercially mature, environmentally benign, and low-cost F-free ethers in high-voltage LMBs.

DOI: 10.1002/anie.202409193

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202409193